Inner workings of Sydney Opera House to receive much-needed makeover

The machinery essential to every musical production at the landmark venue in Sydney Harbour is about to be ripped out and replaced for the first time since it opened in 1973.

Home to 330 performances a year, the venue’s Joan Sutherland Theatre will close for seven months in 2017 for a $45 million upgrade of critical stage equipment.

"I liken it to a classic car, this car has been running day in, day out for 42 years, and now the engine needs to be replaced," Sydney Opera House CEO Louise Herron said.

The Joan Sutherland Theatre holds 330 performances a year. (9NEWS) ()The equipment will be 44 years old by the time it is replaced. (9NEWS) ()

The wear and tear is starting to become very noticeable, not just for the staff behind the scenes, but also for audience members.

"Some of the quieter scenes in the opera and the ballets, you can hear the equipment sometimes in the background," Director of Building Development and Maintenance Greg McTaggart said.

Mr McTaggart said both producers and audiences will benefit from the upgrade.

Staff say the noisy machinery can often be heard during quiet performances. (9NEWS) ()An improvement in the quality of the equipment will mean an improvement in the quality of the productions. (9NEWS) ()

"We'll see the designers of the shows take advantage of that, and they'll be better shows coming through in the future," he said.